How to - Techniques

The secret to making good compost

No matter what you do, organic materials eventually break down. Decay is inevitable. But—and it's a big but—there's a difference between controlled decomposition, as found in a healthy, working compost pile, and the smelly mess of rotting materials in a bin gone bad.

Anyone who has had a bad composting experience (and I confess to having had a few over the years) can tell horror stories of scary-movie magnitude, but the good news is that it's relatively straightforward to create healthy, sweet-smelling compost (often dubbed "gardener's gold" by compost enthusiasts). And the benefits are beyond doubt: compost returns nutrients and organic matter to the soil, feeds beneficial micro-organisms and earthworms, and improves the texture, oxygen-retaining capabilities and moisture-holding capacity of soil. In other words, compost helps create healthy gardens. Beyond its benefit to gardens, however, there's another compelling reason to have some form of composting system in your yard: putting garden and kitchen waste in a compost pile removes these materials (or "good garbage," as my grandmother used to say) from the waste stream. As debates about landfill sites and garbage incineration heat up across Canada, we can all do our bit to reduce the waste our households contribute by heating them up—literally—in a compost bin.

Composting can be seen as a kind of culinary alchemy in which a balanced recipe of ingredients is mixed in a bin or pile. As the mixture breaks down it generates heat, which accelerates the process, and it's eventually transformed into finished compost. The cooking metaphor is apt.

You can take the low-tech approach by simply piling garden cuttings in a corner of the yard and ignoring them for a year. But if you follow the method described on these pages, your compost should be ready to harvest in three to six months.

Choose a containerFirst, you need some kind of structure to contain your composting materials. Options range from store-bought, plastic single bins to homemade, wooden three-bin units. One of the most popular ready-mades is the black plastic SoilSaver, which has a capacity of .36 cubic metres, a locking lid, and doors at the bottoms of two sides. The advantages of this kind of unit are that it's easy to dig finished compost out of the side doors, and it's relatively pest-proof (particularly if you put bricks on top of the lid—urban raccoons have been known to undo the locking mechanism). The black plastic helps the pile to retain the heat it generates, and also to trap solar heat, assuming it's in a sunny location—preferable, but not necessary.

Three-bin units are useful if you've got a large property, since you'll have more leaves, grass clippings and plant debris. When the compost in the first chamber is partially finished, use a pitchfork to transfer it to the second bin, making sure the coarser materials around the sides of the original pile are in the centre of the new one; start from scratch in the first bin. A few weeks later, transfer material in bin two to bin three, and bin one to two, starting over in bin one. This is a good way to aerate the pile; also, materials in the three bins are at various levels of decomposition—an efficient way of making compost.

No matter what type of bin you use, cover it to keep pests out and heat and moisture in, although it also needs vents for airflow. (This is why wooden models typically have spaces between the slats.) Another selling point is a wide opening at the top so you can stir the mixture easily.